The present invention relates generally to control systems for internal combustion engines, and more particularly, to a dynamic electronic throttle position feedforward system.
Many previously known motor vehicle throttle controls have a direct physical linkage between an accelerator pedal and the throttle body so that the throttle plate is pulled open by the accelerator cable as the driver presses the pedal. The direct mechanical linkage includes biasing that defaults the linkage to a reduced operating position also known as idle, in a manner consistent with regulations. Nevertheless, such mechanisms are often simple and unable to adapt fuel efficiency or minimizing regulated emissions or enhancing driveability to changing traveling conditions, and add significant weight and components to the motor vehicle.
An alternative control for improving throttle control and the efficient introduction of fuel air mixtures into the engine cylinders is presented by electronic throttle controls. The electronic throttle control includes a throttle control unit that positions the throttle plate by an actuator controlled by a microprocessor based on sensor input. The processors are often included as part of a powertrain electronic control that can adjust the fuel and air intake and ignition in response to changing conditions of vehicle operation as well as operator control. Protection may be provided so that an electronic system does not misread or misdirect the control and so that unintended operation is avoided when portions of the electronic control suffer a failure.
The throttle control unit that positions the throttle plate must accelerate and decelerate a mass with torque such that a given position is attained. Traditional proportional integral derivative (PID) control of throttle plate position determines control action based upon a single gain on the derivative term of throttle position error. Throttle position error is determined from the difference between the throttle position command and the throttle position sensed. This has a double effect. While the derivative term of traditional PID control opposes fast throttle motion, it gives an added torque boost during a throttle positions command change. Normally, this would be acceptable. Instead of using throttle position error, however, benefit may be gained from handling the throttle position command and the throttle position sensed, separately.
The disadvantages associated with these conventional proportional integral derivative control techniques have made it apparent that a new technique using a dynamic feedforward term for throttle plate positioning is needed. The new technique should provide improved performance over traditional proportional integral derivative control. The present invention is directed to these ends.
It is, therefore, an object of the invention to provide an improved and reliable dynamic electronic throttle position feedforward system. Another object of the invention is to improve performance by handling the throttle position command and the throttle position sensed signals separately.
In accordance with the objects of this invention, a dynamic electronic throttle position feedforward system is provided. In one embodiment of the invention, a method for controlling a positioning device of an internal combustion engine includes the steps of: providing an electric motor for actuating the positioning device with the positioning device applying a torque to the; detecting a commanded position of the positioning device; detecting a sensed position of the positioning device; forming a damping term based upon the sensed position; forming a dynamic feedforward term based upon the commanded position; and forming a control action based separately upon the damping term and the dynamic feedforward term.
The present invention thus achieves an improved dynamic electronic throttle position feedforward system. The present invention is advantageous in that the performance is improved over a feedforward system based on throttle position error.
Additional advantages and features of the present invention will become apparent from the description that follows, and may be realized by means of the instrumentalities and combinations particularly pointed out in the appended claims, taken in conjunction with the accompanying drawings.